﻿//1.define undef 被严格限制在头部
#define Hello
#undef Hello

using System;

namespace define
{
    class Program
    {
        static void Main(string[] args)
        {
#if Hello
            Console.WriteLine("Hello?");
#else
            Console.WriteLine("Or Not");
#endif
            #region 折叠块

#if TRACE
            Console.WriteLine("Hello?");
#else
            Console.WriteLine("Or Not");
#endif

            #endregion
        }
    }
}
